The present invention relates generally to the continuous annealing of drawn wire, and particularly to the process of slip drawing wire in a multi-draw machine and then sending the wire directly and continuously to an annealing apparatus, operating in a slip mode, before the wire is finally drawn and processed.
Generally, drawn wire is formed into a package by being wound on a container, such as a reel or spool, or coiled in a hollow manner without a container. One of the more common ways of annealing the package (either partial or full annealing) is to place the package in a furnace. Depending upon the metal and desired characteristics of the wire, the furnace may or may not have a controlled atmosphere, may or may not have the products of combustion in the furnace atmosphere, and the heat provided in the furnace may come from a variety of sources. The package including the wire is heated to a temperature sufficient to anneal the wire. The package remains in the furnace for a period of time sufficient to allow the heat within the furnace to penetrate the entire amount of wire in the package so that all the wire attains the annealing temperature. After this, the package may be discharged from the furnace, to cool naturally, or means may be used to effect a more rapid rate of cooling; or, the package may be cooled in the furnace to a specified temperature and then discharged from the furnace and cooled further. In any case, the package is cooled to a temperature that allows handling of the package.
It can be appreciated that these processes take a considerable amount of time and energy, as there is substantial time involved in heating the package and wire up to annealing temperature, additional time for the total package to reach thermal equilibrium, and finally the needed time for cooling either outside or inside the furnace. Further, energy is wasted in heating the container, as no purpose is served in heating the container. In addition, the heating and cooling of the total package metallurgically weakens the container such that container life is shortened; hence, replacement costs for the package are involved when using annealing furnaces.
It is, however, not unknown to continuously anneal wire in cooperation with a continuous drawing operation. In U.S. Pat. No. 3,630,057 to Strohmeier, a plurality of components are slaved together, in tandem, to continuously draw and anneal steel wire, before a final drawing operation (at a location remote from the initial drawing operation), after the wire has undergone a pickling process and copper plating. Slaving is effected by a drive 10 which functions as an accumulator, "The wire 16 which leaves . . . drive 10 is virtually under no tension and is . . . passed with the aid of rollers through . . . bath 11", column 2, lines 56 to 59. From bath 11, the wire is directed to "a drawing unit 12 which has a speed of operation that is variable.", column 2, lines 70 and 71. Hence, the operation of Strohmeier appears to be a non-slipping one, as a slipping process does not need accumulating devices in the line. Rather, overall speed of a slip process is set by a final capstan driven by the slip-type drawing machine.
A system similar to the above Strohmeier patent is shown in U.S. Pat. No. 3,826,690 to Bleinberger et al, in which a multi-draw machine produces aluminum wire continuously for an annealing process involving electromagnetic coupling using a transformer and a loop of the wire. An intermediate cleaning process is included, and a single draw of the wire is made at a location separate from the drawing machine and before the wire is directed to an extruding head for insulating the wire. Again, as in the case of the Strohmeier patent, the individual components and processes are slaved together in a tandem, non-slip manner using an accumulator 29 to control wire tension between drawing and annealing.
U.S. Pat. No. 3,779,055 to Goyffon shows a slip drawing machine continuously feeding wire to enameling apparatus from the last die of the machine. There is no final drawing operation, as in Strohmeier and Bleinberger et al, and Goyffon is concerned with permitting the enameling machine to govern the overall speed of the two devices without rigid synchronization between the two. In this manner, independent operation of the two processes is also provided.